[C#]使用WM_SYSCOMMAND訊息控制螢幕模式切換

要控制螢幕的開啟、關閉，可透SendMessage發送WM_SYSCOMMAND訊息，wParam參數傳入SC_MONITORPOWER，lParam參數則傳入螢幕的模式。

參數方面參閱WM_SYSCOMMAND Message，裡面清楚的帶出WM_SYSCOMMAND為0x0112、SC_MONITORPOWER為0xF170、與其對應的lParam。

使用上就像下面這樣：

    [DllImport("user32.dll")]
    private static extern int SendMessage(int hWnd, int Msg, int wParam, int lParam);

    const int SC_MONITORPOWER = 0xF170;
    const int WM_SYSCOMMAND = 0x0112;
    ...
    SendMessage(-1,  WM_SYSCOMMAND, SC_MONITORPOWER , -1);
    SendMessage(-1,  WM_SYSCOMMAND, SC_MONITORPOWER , 1);
    SendMessage(-1,  WM_SYSCOMMAND, SC_MONITORPOWER , 2);

這邊為方便後續使用，將程式整理成類別，有需要的自行取用。

public static class MonitorControler { [DllImport(“user32.dll”)] private static extern int SendMessage(int hWnd, int Msg, int wParam, int lParam);

    const int SC_MONITORPOWER = 0xF170;
    const int WM_SYSCOMMAND = 0x0112;
    //const int SC_SCREENSAVE = 0xF140;
    
    public enum MonitorMode : int
    {
        MONITOR_ON = -1,
        MONITOR_STANBY = 1,
        MONITOR_OFF
    }

    public static void ChangeMonitorState(MonitorMode mode)
    {
        SendMessage(-1, WM_SYSCOMMAND, SC_MONITORPOWER, (int)mode);
    }

    public static void MonitorOff()
    {
        ChangeMonitorState(MonitorMode.MONITOR_OFF);
    }

    public static void MonitorOn()
    {
        ChangeMonitorState(MonitorMode.MONITOR_ON);
    }

    public static void MonitorStandBy()
    {
        ChangeMonitorState(MonitorMode.MONITOR_STANBY);
    }
}

Link

 WM_SYSCOMMAND Message

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